Tiny comb jellies, each .039 of an inch (10 millimeters) in diameter, whirl around like beach balls. The gelatinous creatures get their name from their propulsion system: Cilia, the hairlike structures that provide locomotion in many marine species, are fused into “combs” that pulsate, moving the animals through the water.
	A thumbnail-size pelagic mollusk moves almost invisibly through the aquarium sea. Its general name locates it—pelagic animals live in the open ocean—and identifies it as a member of the phylum Mollusca, which encompasses a huge group of animals. next page

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